I. Field of the Invention
This invention relates generally to remote entry systems and, more particularly, to a hands-free remote entry system for vehicles.
II. Discussion of the Related Art
Remote entry systems for vehicles have been in use for several years. These systems provide safety and convenience for a user entering or exiting a vehicle. Some of the typical features offered by these systems allow the user to lock/unlock doors and arm/disarm auto theft systems in a remote manner.
For instance, many remote entry systems will utilize a key fob with an infrared transmitter which is received by an infrared sensor positioned on the vehicle. When the user is within range, the user actuates a button on the key fob to either lock or unlock all the vehicle doors. Concurrently with the locking or unlocking, an anti-theft system is typically armed or disarmed. However, one disadvantage of this type of system is that the user must manually actuate the key fob to achieve the desired result.
In order to attempt to eliminate this disadvantage, some remote entry systems now operate in a hands-free manner. For example, one system currently being utilized employs a key fob which uses an internal motion sensor. As a user walks or moves, the key fob on the user detects this motion and continuously transmits a signal while the motion is detected. If the user is near the vehicle, the vehicle will receive this signal and unlock all the doors. Thereafter, the system will "time out" and lock all the doors.
Thus, this system eliminates the need for the user to manually actuate the key fob. However, this system has several disadvantages. First, if the user is merely walking past the vehicle with the key fob, the vehicle will inadvertently unlock the doors when not required. This would leave the vehicle subsequently open to theft or vandalism. Second, when the user is inside the vehicle, the user may unintentionally cause the doors to unlock by moving the key fob inside the vehicle. This may allow a child to open the vehicle door as the vehicle is moving or allow an intruder to enter the vehicle while the user attempts to lock the vehicle. Finally, battery life of the key fob is also greatly reduced. For example, if the key fob is in the user's pocket and the user is taking a walk, the key fob will continuously transmit signals and thereby degrade the battery.
Another hands-free system currently in use either employs the key fob or the vehicle to periodically emit a signal, such as every 100 milliseconds. As the user approaches the vehicle, the key fob or the vehicle receives this signal and unlocks the door. Again, this system may cause the vehicle to be unlocked unintentionally and inadvertently, as well as reduce the battery life of the key fob or the vehicle because of the continuous periodic transmissions. Additionally, both of the above systems typically open all of the doors and not just the entering door. This allows the possibility of having an intruder enter through another door.
What is needed then is a hands-free remote entry system which does not suffer from the above-mentioned disadvantages. This will, in turn, eliminate the inadvertent and unintentional locking or unlocking of the vehicle doors, increase battery life in the key fob and the vehicle, eliminate opening all the doors simultaneously and eliminate the continuous transmission of unnecessary signals. It is, therefore, an object of the present invention to provide such a hands-free remote entry system and method therefor.